Catalytic activity and electron configuration of the EDA complexes of phthalocyanine with alkali metals. Hydrogen adsorption and the H2—D2 exchange reaction

Abstract

Hydrogen adsorption and H₂—D₂ exchange reaction on the stoichiometric EDA (electron donor-acceptor) complexes of various phthalocyanines with alkali metals (Li, Na, K, Rb) were studied and their behaviour correlated with the electronic structure of the complexes.

It was demonstrated that the activity of the complexes for the HZ—D₂ exchange reaction, D₂+ HZ ⇌ HD + DZ, where HZ represents the EDA complexes of phthalocyanine, was only dependent upon the number of electrons donated to the π-conjugated system of the ligand, irrespective of the kind of central metal ion. On the other hand, the H₂—D₂ exchange reaction was markedly affected by the central metal cations, which suggests that the hydrogen dissociation takes place within the crystal field of the metal ions

The effect of preadsorbed carbon monoxide on the hydrogen chemisorption and the exchange reaction was also studied, and from these results, the nature of the reaction sites discussed.